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1.
Food Chem ; 305: 125450, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31499291

RESUMO

A round robin comparison was performed in order to test the performance of a recently developed LC-MS/MS method for quantification of 6 folate forms. Eighty-nine samples representing the food groups of fruits, vegetables, legumes, cereals, dairy products, meat, and offal were analyzed by two LC-MS/MS methods and a microbiological assay (MA). A plant-origin deconjugase enzyme (Arabidopsis thaliana) for deconjugation of folates (PE-LC-MS/MS), or animal-origin deconjugase (rat serum and chicken pancreas) (AE-LC-MS/MS) was used in the LC-MS/MS methods, each in a single enzymatic step. In contrast, the MA involved tri-enzyme extraction including human plasma as a deconjugase. A significant bias of 17% lower and 25% higher results was found when PE-LC-MS/MS was compared to MA and AE-LC-MS/MS, respectively. The PE-LC-MS/MS provides fast quantification of various folate vitamers and total folate content, which could be a proper substitute to the currently standardized but imprecise and time-consuming microbiological assay in the future.

2.
PLoS One ; 14(2): e0212255, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30789924

RESUMO

Folates play a key role in the prevention of neural tube defects in newborns. Thus, it is important to reliably determine the bioavailability of folates from various foods. Accurate analytical methods are essential for quantifying blood-folates, especially in human studies. Here, we present the development and validation of a sensitive method using stable isotope dilution liquid chromatography coupled with mass spectrometry for determining various folates in plasma. Moreover, this study reports the applicability of the developed method to a human pilot study using strawberries as a test food. Validation of the assay revealed the precision, sensitivity, and accuracy of the method in determining the predominant 5-methyltetrahydrofolate in plasma. This method was also applicable for the screening of individual folate status using finger prick blood and for monitoring the post-absorptive plasma-concentration curve. Moreover, the human study revealed a high recovery of strawberry folates with a calculated relative bioavailability of 96.2%. Thus, the developed method enables prospective bioavailability studies. This work also confirmed, via human studies, that strawberries are a rich and natural source of folates that are available for human metabolism.


Assuntos
Tetra-Hidrofolatos/farmacocinética , Adulto , Cromatografia Líquida , Feminino , Fragaria/química , Humanos , Técnicas de Diluição do Indicador , Masculino , Espectrometria de Massas , Defeitos do Tubo Neural/sangue , Defeitos do Tubo Neural/tratamento farmacológico , Sensibilidade e Especificidade , Tetra-Hidrofolatos/administração & dosagem
3.
Front Chem ; 6: 11, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29468149

RESUMO

Folates play an important role in the human body and a deficiency of this vitamin can cause several diseases. Therefore, a reliable analytical method is crucial for the determination of folate vitamers in strawberries and other dietary folate sources. A stable isotope dilution LC-MS/MS method for analyzing folates in food was developed and validated. The folate vitamers Pteroylmonoglutamic acid, tetrahydrofolate, 5-methyltetrahydrofolate, and 5-formyltetrahydrofolate were quantified using 13C-labeled internal standards. Validation of the assay was accomplished by determining linearity, precision, recovery, limit of detection, and limit of quantification and revealed to be a precise, sensitive, and accurate method to determine folate vitamers. Strawberries are worldwide consumed and known to be a good dietary source of nutritive compounds. Using this method, folate concentrations in selected commercial strawberry cultivars and experimental breeding lines grown in Germany and Australia were investigated. Total folates varied from 59 to 153 µg/100 g on fresh weight basis. Furthermore, folate content after lyophilizing or freezing did not show any significant differences compared to fresh strawberries. However, significant losses of total folates in pureed strawberries could be observed after 5 days of storage with only 16% of the original concentration retained. In summary, some of the investigated strawberry cultivars/breeding lines can be considered as rich dietary sources of natural folates.

4.
Front Nutr ; 2: 3, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25988132

RESUMO

This study evaluates the potential mechanism of action and bioactivity of black tea and black tea pomace for type 2 diabetes prevention via inhibition of carbohydrate hydrolyzing enzymes. Black tea leaves were extracted in hot water and black tea pomace was extracted in 70% acetone. The phenolic content of the water extract (WBT) and pomace acetone extracts (AOBT) were 5.77 and 8.9 mg/mL, respectively, both based on the same concentration of solid tea in the extract. The water extract was subjected to C18 extraction and the resulting hydrophobic fraction (HBBT) was further subjected to LH-20 extraction to recover a low molecular weight phenolic enriched fraction (LMW) and a high molecular weight enriched fraction (HMW). The phenolic content of the LMW and HMW fraction were 1.42 and 2.66 mg/mL, respectively. Among water extracts the HMW fraction was most bioactive against α-glucosidase (IC50 = 8.97 µg/mL) followed by HBBT fraction (IC50 = 14.83 µg/mL). However, the HBBT fraction was the most bioactive fraction against α-amylase (IC50 = 0.049 mg/mL). The black tea pomace (AOBT) had significant α-glucosidase inhibitory activity (IC50 = 14.72 µg/mL) but lower α-amylase inhibitory activity (IC50 = 0.21 mg/mL). The phenolic profiles for LMW and HMW fractions were evaluated using HPLC and the differences between the two profiles were identified. Further research is underway to identify and evaluate the phenolic compounds that are present in the HMW fraction. Our findings suggest that black tea and black tea pomace has potential for carbohydrate hydrolyzing enzyme inhibition and this activity depends on high molecular weight phenolic compounds.

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